In many medical environments, a medical fluid is injected into a patient during diagnosis or treatment. One example is the injection of contrast media into a patient to improve Optical Imaging, Nuclear Medicine, CT, Angiographic, Magnetic Resonance or Ultrasound imaging, or any diagnostic imaging or therapeutic application using a powered, automatic injector.
Injectors suitable for these and similar applications typically must use a relatively large volume syringe and be capable of producing relatively large flow rates and injection pressures. For this reason, injectors for such applications are typically motorized, and include a large, high mass injector motor and drive train. For ease of use, the motor and drive train are typically housed in an injection head, which is supported by a floor, wall, or ceiling mounted arm.
The injection head is typically mounted on the arm in a pivotal manner, so that the head may be tilted upward (with the syringe tip above the remainder of the syringe) to facilitate filling the syringe with fluid, and downward (with the syringe tip below the remainder of the syringe) for injection. Tilting the head in this manner facilitates removal of air from the syringe during filling, and reduces the likelihood that air will be injected into the subject during the injection process. Nevertheless, the potential for accidentally injecting air into a patient remains a serious safety concern.
In addition to the injection head discussed above, many injectors include a separate console for controlling the injector. The console typically includes programmable circuitry which can be used for automatic, programmed control of the injector, so that the operation of the injector can be made predictable and potentially synchronized with operations of other equipment such as scanners or imaging equipment.
One particular operational routine performed by the injector system is that of filling the syringe with contrast. This filling sequence for a power injector typically requires the use of both hands by the operator. A contrast container is held in one hand in close proximity to the injector while the other hand operates the injector controls to retract the plunger so as to fill the syringe. Even in injectors which can auto-fill a preset volume, the use of both hands by the operator is still required when initially starting the auto-fill sequence.
Accordingly, a need exists to simplify the syringe sequence in power injectors so that an operator can have at least one hand available to perform other activities during the entire operation of filling a syringe.
Occasionally when filling a syringe, the filling sequence can be problematic in that if it is performed too fast, the contrast media is aerated or if it is performed too slow, the sequence can take an unreasonable amount of time to complete. There is, therefore, based on the contrast media and the possible presence of air in the fill tube, a maximum filling rate for contrast media that will avoid aerating the contrast media during filling. While this speed can be programmed in the injector and automatically used, an operator typically monitors the syringe filling to further reduce the likelihood of aeration of the contrast media. A need exists for a filling sequence that permits filling of the syringe with contrast fluid faster than the maximum filling speed attainable if air is present in the fill tube.